Refining Ounce-Equivalents Using the EAA-9 Approach for Protein Scoring and Dietary Guidance.

Background: The US Department of Agriculture (USDA) Protein Food ounce-equivalents are designed to identify plant sources of protein foods and provide serving size substitutions. Although the ounce-equivalent concept is simple, it fails to generate equivalent exchanges for protein or essential amino acids (EAAs).

Objective: To accurately define the EAA content of USDA Protein Food ounce-equivalents, to develop a more accurate food exchange list, and to evaluate the EAA-9 protein quality framework as a tool for determining precise EAA-equivalent substitutions.

Design: The USDA National Nutrient Database (Standard Reference Legacy) and the EAA-9 protein quality model were used to evaluate the validity of the USDA Protein Food ounce-equivalents for creating equivalent protein and EAA substitutions. The EAA-9 framework then established EAA-9 Equivalence serving sizes to meet EAA requirements.

Main outcomes: EAA composition in protein foods was assessed. EAA-9 Equivalence servings were developed.

Statistical analysis: EAA composition was calculated for USDA Protein Food ounce-equivalents. EAA-9 scores were calculated for protein foods and compared using an egg's EAA composition as a standard. MyPlate Kitchen Recipes were used to apply USDA Protein Food ounce-equivalent exchanges and EAA-9 Equivalence servings.

Results: The USDA Protein Food ounce-equivalents are not equivalent in protein or EAAs, with the disparity ranging from 1 ounce-equivalent of chicken breast with 9.1 g protein and 4.0 g EAAs to 1 ounce-equivalent of almonds with 3.0 g protein and 0.9 g EAAs. Using the USDA serving of 1 egg as a standard for comparing protein food groups, <15% of beans, peas, and lentils and 0% of nuts and seed ounce-equivalents achieve the EAA composition of an egg. EAA-9 Equivalence servings are truly equivalent, with each serving providing a reliable and interchangeable protein source. The EAA-9 Equivalence servings have been calculated and are now available for all USDA Standard Reference Legacy foods with a complete EAA profile, offering a resource for exchanges that ensure EAA requirements are met.

Conclusions: Creating ounce-equivalent substitutions for protein foods requires creating food exchanges that assure EAA requirements are met. The USDA Protein Food ounce-equivalents provide inadequate guidance for balancing EAA requirements.